Electric forging and heat-treating furnace



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F. G. DAWSON. ELECTRIC FORGING AND HEAT THEATING FURNACE.

lAPPLICATION FILED IAN. II. 1921 I 6 f1.1 'l 9 'ZR- 9 7 I f l PatentedSept. 26, 1922. 1

' in the different phases may Patented Sept. 2.6, 1922.

UNITED STATES PATENT OFFICE.

ELECTRIC FORGIN'G AND HEAT-TREATING FURNACE.

Application led January 11, 1921. Serial No. 436,617.

To aLl whomA t may concern Be it known that I, FREDERICK Gr. DAW- soN, av citizen of the United States, and a resident of Detroit, in the county of Wayne and State of Michigan, have invented a new and Improved Electric Forging and Heat- Treat-ing Furnace, of which the following is a full, clear, and exact description.

This invention relates to an electric forging and lieat-treating furnace, and has for an object the provisionv of a simple and effi-` cient furnace structure ,wherein the electrodes co-operate to produce the desired amount of heat without the establishment of a free burning are, whereby the need for complicated automatic controllers is eliminated.

Another object resides in th provision of simple and easily operable means whereby when the furnace isconnected to an alternating current system the various electrodes be balanced in a simple and ready manner with respect to the current flowing in each electrode.

A further object resides in the arrangement of the electrodes with respect to the charge to be heated, whereby the charge is uniformly and quickly heated.

A still further object resides i'n the particular constructionv and arrangement of parts hereinafter described and claimed and shown in the accompanying drawings.

In general, the invention comprises an electric furnace structure the walls of which may be made of any suitable heatfresisting and insulating material within which are contained a plurality of electrodes, one of which is a common electrode resting upon blocks and-thereby spaced from the oor of the furnace, the others of which rest by gravity on the common each connected to different phases of an alternating current system, the common electrode being connected to the neutral wire by sa-id system. The contact between the common electrode and the other electrodes is regulated by the provision of a plurality of weights or other similar operating devices, whereb the pressure of contact may be varied. n a single-phase system only one movable electrode need be used.

electrode and are The invention is illustrated in the drawings ,lof which- Figure 1 is a vertical longitudinal sec tion of the furnace; and

Figure 2 is a transverse section taken on the line 2 2 of Figure 1. The form of furnace shown in the drawings, which represents merely a preferred embodiment of my invent-ion, comprises an inner lining wall 1 of any suitable material having high refractory properties, such as a compound of carbon and silicon and aluminum oxide. Surrounding this is an Aintermediate wall or lining composed-of a fairly good refractory material, such as corondite or bauxite. outer wall 3 of refractory material of an suitable composition containing silicon.

-casing 4 of sheet iron encloses these-various refractory wal-ls.

vVit-hin these walls there is a heating chamber 5. Extending downwardl into this chamber from the upper face of t e furnace are` a plurality of vertical electrodes 6. These electrodes pass through suitable openings 1n the above-mentioned. walls and are surrounded by a cooling jacket 7, which may be 'of any suitable type and connected to a source of-cooling fluid, and by a packing box 8 of any suitable design which may be filled with suitable material to prevent the leakage of gas to or from the furnace. The

upper ends of the electrodes 6, extending above the furnace, are connected to a collar 9 to which a cable- 10 is attached. This cable'passes over pulleys 11 and 12 and supports at its .other end a weight 13. Within the furnace the lower faces of the electrodes 6 are adapted to rest upon an electrode 14 which is in the form of a block of carbon, or other' suitable material, extendin lengthwise down the middle of the cham r 5 and supporting and engaging with the lower faces of the electrode 6. This common electrode 14 is supported from the floor 15 of the furnace by means of a plurality of spacing bricks 16 which are made of any suitable highly refractory material. These bricks support the electrode 14 and space it above the floor 15 a desired distance. The material to be heated is introduced into the fur- Surrounding this wall is an nace through a lateral opening 17 and placed in position beneath the electrode 14.

Extending beneath the Hoor 15 of the furnace is a sheet-metal plate 18 which is connected to the neutral wire of a polyphase system7 each of the electrodes 6 being connected to a. different phase of the system In the operation of the device, when the above mentioned connections are made the poor Contact between the lower face of the electrodes 6 and the upper face of the electrode 14 causes a heating action to take place. This causes the electrode 14 to heat up, and this heatis transmitted to the. n1aterial beneath this electrode. The regulation of the various electrodes to balance the current in each of the phases may be effected by the adjustment of the weights 13 to vary the contact pressure between the electrodes G and 14. It will be noticed that the metal is heated by radiation and not by the heat of an arc. The ends of the furnace can be removed in any suitable manner so as to restore the linings and repair the parts if necessary. Because of the fact that there is a Very poor circulation of air in the furnace through the lateral opening' 17, and that the electrode 14 becomes white hot, the atmosphere will be a reducing one. The inside lining of a compound of carbon and silicon tends to efiiciently retain the heat, whereby a high tempera-ture can be maintained and rapidly reached by this furnace. A consideration of the above mentioned description will show that the operation of this furnace depends merely upon av poor contact between two electrode surfaces, and not upon a free burning arcs which requires complicated apparatus to regulate. The regulation of the current in this furnace is a comparatively simple matter. A high tem- -bearing by reason of perat-ure is maintained with a voltage in the neighborhood of 40 volts, and in a furnace the structure of which is extremely simple.

Vhat I claim is:

1. An electric furnace comprising a heat ing chamber, a common electrode within said heating chamber. a plurality of other electrodes extending into the chamber and bearing upon a surface of the common electrode, the other electrodes bea-ring on the common elect-rode by reason of theiriveight, and means for adjusting the pressure between t-he common electrode and the other electrodes. e l

2. An electric furnace comprising a heating chamber, a horizontally extending electrode disposed above the fioor of the furnace7 a plurality of vertically extending electrodes their weight on the upper surface of the horizontally extending electrode, and means for adjusting the contact pressure between the vertical and horizontal electrodes, the space between the horizontal electrode and the fioor of the furnace forming a chamber for the charge to be heated.

3. An electric. furnace comprislng a heating chamber, a plurality of walls of refractory material surrounding said chamber. a horizontally extending electrode within the chamber and spaced above the floor thereof. a plurality1 of vertically extending electrodes earing. upon the upper face of the horizontal electrode by reason of their weight. and means for adjusting the contact pressure be tween the horizontal and the vertical electrodes, the space between. the horizontal electrode and the Hoor of the furnace serving as a chamber for the materia-l to be heated.

FREDERICK G. DAWSON.- 

